Electric thermostatic fire-alarm contacts.



APPLICATION FILED DEC. 26, 1912.

Patented Nov. 17. 1914.

in (1'1: 11 6 0 I VVitne-xses UNITED STATES PATENT OFFICE.

HENRY DIXON, OF TORONTO, ONTARIO, CANADA, ASSIGNOB. TO FRANKLIN DWIGHT CURTIS, OF HAMILTON, ONTARIO, CANADA.

ELECTRIC THERMOSTATIC FIRE-ALA CONTACTS.

Specification of Letters Patent.

Patented Nov. 17, 1914.

Application filed December 28, 1912. Serial No. 738,788.

To all whom it may concern:

Be it known that I, HENRY DIXON, of the cityof Toronto, in the county of York and Province of Ontario, Canada, have invented certain new and useful Improvements in Electric Thermostatic Fire-Alarm Contacts; and I do hereby declare that the followin is a full, clear, and exact description thereo reference bein had to the accompanying drawings, whic form part of this specification.

The present invention relates to im rovements in a device or the detection an location of fire, and articularly to that class in which a therma ly-actuated contact automatically closes or opens an electric circuit and sets in action the alarm device; and the 0b 'ect of the invention is to overcome the di culties that are encountered owin to the uncertainty of contact occasioned y the presence of minute particles of dust or oxidation between the contact-points, and the detriment due to the tendency of the contacts to vibrate, serious defects in the use of previous devices of this class; and furthermore to provide a positively reliable and highly sensitive thermally-actuated contact device, applicable alike, for high or low redetermined temperatures and under varyin climatic conditions.

%1haracteristic of the present invention is the inclosing ofthe electric contacts within a hermetically sealed chamber, in part formed by a thermally-actuated resilient dia hragm, consisting of elements having di 'erent coefiicients of expansion and con traction, of such construction and form as to set up therein a diflerential stress relatively proportionate to the change in temperature from that of normal conditions.

The invention consists in art of the incorporation of a non-conducting or heat obstructing medium within the inclosed space contiguous to the resilient diaphragm, whereby the slightest change in temperature beyondthat predetermined for setting in operation the alarm device is not prematurely lost through dissipation within the walls of the heavier material forming the case or body of the thermostat, but operative in defleeting the highly sensitive resilient diaphragm irrespective of the attained temperature of the inactive parts of the device, and certain details of construction, as hereinafter set forth and illustrated in the accompanying drawings, in which similar fi ures of reference refer to like parts throng out.

Figure 1 is a view in perspective showing more particularly the outer casing or protector of the thermostat. Figs. 2 and 3 are views in lan of the back and front, respectively, o the thermostat. Fig. 4 is a view of the device, partly in vertical transverse section with the thermostat shown therein in elevation; and, Fig. 5 is a vertical transverse sectional view showing the interior arrangement of the several parts of the thermostat.

Cast or malleable iron is preferable for the material of which the case 1 of the thermostat is made, the expansion or contraction due to the changes of temperatures beinfi lsmo small comparatively as to be negligible. 0 case 1 forms the bottom and sidewalls of the chamber 2, which are of sufiicient thickness to withstand any undue strain brought about throu h careless manipulation when in the act 0 attaching or re lati the device, and to eliminate practically al defleotion or vibration. The case 1 is circular in shape and provided with lateral lugs 3, by means of which it is suspended within the outer casing 4 and attached thereto by screws 5, which enter corresponding lugs 6 integral with the outer casing. The outer casing or protector 4 is of substantially openwork construction, preferably ornamental in design and adapted to be mounted upon a base. The circular wooden base 7, shown in this instance, may be replaced by a suitable condulet or metal base, and provided provision is made for the connecting wires the base can be dispensed with entirely, if found desirable. The openwork construction of the outer casing insures the slightest variation in temperature being readily communicated to the thermostat contained therein by the free circulation of the surrounding air.

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H E N R Y DIXON. '1' t. 1685082 (hm. B. J'sixzurcwjrm H. M. EAST. 

